Please Help - Regex

Hello,

I have a few strings with the patterns : "1234AB", "1234ABC", "AB1234CDE" which I am trying to match. For starters, i don't know if I have the regular expressions correct. When I compile, I get some of the desired results but I also get some duplicates. Can someone please help me figure out the proper regular expression?.

Also, I was trying to match more than one pattern and I am not doing too well with that either.